This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-371786, filed on Dec. 5, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a projection type image display system and a color correction method thereof, and more particularly to a technique to correct a change or the like in color or luminance (corresponding to light intensity).
2. Description of the Related Art
There has been proposed a multi-projection display system which combines partial images from a plurality of projectors (image displaying means) and displays them as one image. In this multi-projection display system, it is important to correct a difference in color or brightness generated due to a difference in characteristic between respective displays (projectors).
For example, Jpn. Pat. Appln. KOKAI Publication No. 2001-54131 discloses a method which measures characteristic data of each display by using measuring means such as a spectrophotometer, an imaging device, a calorimeter or an illumination photometer and corrects a difference in color reproduction property between the respective displays based on a measurement result. Consequently, images projected on a screen by a plurality of the displays can be recognized as one image from which discontinuity can not be felt.
However, in the above-described correction method, when an age-based change has occurred in each display and correction is again necessary, a user or a service personnel must perform measurement by the above-described measuring means, which is very troublesome.
Further, in order to correct a white balance or a convergence error, light detecting means may be provided inside or outside the displays in some cases. For example, Jpn. Pat. Appln. KOKOKU Publication No. 7-121129 proposes to arrange a mirror (or a half mirror) having the dedicated finishing applied to a surface thereof in a light path and arrange the light detecting means on a back side of the mirror. Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 7-284120 proposes to arrange light detecting means in an over scan portion of the display. As a result, the projected light from each display can be measured by the light detecting means, and the white balance or the convergence error can be corrected.
However, when the mirror (or the half mirror) having the dedicated finishing applied to the surface thereof is used, a partial or overall reduction in quantity of light occurs on the screen due to application of the finishing on the surface of the mirror, thereby deteriorating the image quality.
Moreover, for example, Jpn. Pat. Appln. KOKAI Publication No. 8-292495 proposes a display system which warns a replacement timing of a lamp by detecting a change in brightness of a light source. As a result, it is possible to be aware of the necessity of replacement of the lamp before the lamp is burned out.
In the above proposal, however, only notification of information concerning the lamp replacement is assumed. In the multi-projection display system, therefore, it is not possible to obtain information that replacement of the lamp is unnecessary but simplified color correction between the displays is required, or information that correction using the measuring means is required instead of the simplified correction.
In this manner, the prior art has a problem that correction takes a lot of trouble and is complicated, a problem that the image quality is deteriorated due to the correcting means, or a problem that the necessity of the correction processing can not be notified.
It is an object of the present invention to provide a projection type image display system or the like which can reduce the complication of correction, suppress the deterioration in image quality due to the correcting means, or readily recognize the necessity of the correction processing.
According to a first aspect of the present invention, there is provided a color correction method of a projection type image display system which projects an image from color image displaying means onto a screen, the method comprising: a step of measuring an initial XYZ-tristimulus value of an image projected onto the screen at the time of initial adjustment; a step of measuring an initial luminance value of the image projected onto the screen at the time of initial adjustment; a step of obtaining a correlation between the initial XYZ-tristimulus value and the initial luminance value; a step of measuring a maximum luminance value of each of primary colors of an image projected onto the screen upon lapse of a predetermined time from the initial adjustment; a step of estimating an XYZ-tristimulus value of the image on the screen upon lapse of the predetermined time based on the maximum luminance value and the correlation; and a step of calculating a color correction coefficient based on the estimated XYZ-tristimulus value.
According to a second aspect of the present invention, there is provided a projection type image display system comprising: color image displaying means for displaying an image to be projected onto a screen; means for storing a correlation between an initial XYZ-tristimulus value of an image projected onto the screen at the time of initial adjustment and an initial luminance value of the image projected onto the screen at the time of initial adjustment; luminance measuring means for measuring a maximum luminance value of each of primary colors of an image projected onto the screen upon lapse of a predetermined time from the initial adjustment; means for estimating an XYZ-tristimulus value of the image on the screen upon lapse of the predetermined time based on the maximum luminance value and the correlation; and means for calculating a color correction coefficient based on the estimated XYZ-tristimulus value.
According to a third aspect of the present invention, there is provided a projection type image display system comprising: image displaying means for displaying an image; a projection optical system which projects the image displayed by the image displaying means; and a screen which displays the image projected by the projection optical system, wherein the projection optical system includes: a reflecting mirror which reflects light from the image displaying means toward the screen and is configured in such a manner that a reflecting surface has a uniform reflectance; and luminance measuring means which is provided on a surface opposite to the reflecting surface and measures a luminance value of light transmitted through the reflecting mirror from the image displaying means.
According to a fourth aspect of the present invention, there is provided a projection type image display system which displays a single color image by using a plurality of partial color images, comprising: a plurality of partial color image displaying means each of which receives color image data and displays a partial color image; a plurality of luminance measuring means each of which measures a luminance value of an image displayed by a corresponding one of the partial color image displaying means; comparing means for comparing a plurality of the luminance values measured by the plurality of the luminance measuring means; and warning means for performing warning based on a comparison result obtained by the comparing means.
According to a fifth aspect of the present invention, there is provided a projection type image display system which displays a single color image by using a plurality of partial color images, comprising: a plurality of partial color image displaying means each of which receives color image data and displays a partial color image; a plurality of luminance measuring means each of which measures a luminance value of an image displayed by a corresponding one of the partial color image displaying means; evaluating means for numerically evaluating an age-based change factor of an image based on a measurement result obtained by the luminance measuring means; and warning means for performing warning based on an evaluation result obtained by the evaluating means.
According to a sixth aspect of the present invention, there is provided a projection type image display system comprising: image displaying means for displaying an image; a projection optical system which projects the image displayed by the image displaying means; and a screen which displays the image projected by the projection optical system, wherein the projection optical system includes: a reflecting mirror which reflects light from the image displaying means toward the screen; luminance measuring means for measuring a luminance value of the light reflected by the reflecting mirror; and reflecting mirror driving means which changes an angle of the reflecting mirror in such a manner that the luminance measuring means is not irradiated with the light reflected by the reflecting mirror when projecting a regular image and that the luminance measuring means is irradiated with the light reflected by the reflecting mirror when measuring a luminance value.
According to a seventh aspect of the present invention, there is provided a projection type image display system comprising: image displaying means for displaying an image; a projection optical system which projects the image displayed by the image displaying means and has luminance measuring means for measuring a luminance value of light from the image displaying means; a screen which displays the image projected by the projection optical system; moving means for moving the luminance measuring means in such a manner that the luminance measuring means is not irradiated with light from the image displaying means when projecting a regular image and that the luminance measuring means is positioned between the screen and the image displaying means when measuring a luminance value; and shielding means for preventing external light which is transmitted through the screen and enters the image displaying means side.
According to an eighth aspect of the present invention, there is provided a projection type image display system comprising: image displaying means for displaying an image; a projection optical system which projects the image displayed by the image displaying means and has luminance measuring means for measuring a luminance value of light from the image displaying means; a screen which displays the image projected by the projection optical system; and moving means for moving the luminance measuring means on a surface of the screen opposite to a surface on the image displaying means side of the screen in such a manner that the luminance measuring means is not irradiated with light from the image displaying means when projecting a regular image and that the luminance measuring means is irradiated with light from the image displaying means when measuring a luminance value.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.